1. Field of the Invention
The present invention relates to a magnetic memory and to a method of manufacturing same.
2. Related Background Art
In recent years, MRAM (Magnetic Random Access Memory) is attracting attention as a memory device for information processors such as computers and telecommunications devices. Since MRAM stores data by magnetism, it has the advantage that it does not suffer from the inconveniences associated with a volatile memory such as DRAM (Dynamic Random Access Memory) or SRAM (Static RAM), where information would be lost if for example the power supply were interrupted.
MRAM is dramatically superior as regards access speed, reliability and poser consumption compared to a nonvolatile storage means like a conventional flash EEPROM or a hard disk drive. Therefore, MRAM has the potential to assume all the functions of volatile memories such as DRAM and SRAM, and the functions of nonvolatile storage means such as flash EEPROM and hard disk drives.
MRAM comprises a magneto-resistance effect element using the TMR (Tunneling MagnetoResistance) effect or the GMR (Giant MagnetoResistance) effect. When writing data to MRAM current is passed through a write interconnection situated near the magneto-resistance effect element, the magnetization direction of a magnetosensing layer (free layer) in the magneto-resistance effect element changing due to the magnetic field generated by this current When reading data from MRAM, stored data is distinguished depending on the resistance of the magneto-resistance effect element when current is passed through a read interconnection electrically connected to the magneto-resistance effect element.
However, the magnetic field generated around the write interconnection may affect adjacent elements, and cause a malfunction. A magnetic yoke is therefore placed around the write interconnection in an attempt to inhibit the effect on adjacent elements (e.g., Patent document 1: JP-A No. 2004-128430).